I'm trying to interface MCP3903. I haven't really don't any SPI interfacing before and I can't seem to find clear enough answer for newbs. Please bare with me.

I'm trying to use this library. http://www.kerrywong.com/2014/05/10/mcp3903-library/

On the website there is the following circuit diagram.

enter image description here

I can see SDI, SDO pins on the ESP module, how do I connect the SCK and CS pins? If they can be any pins how do I declare them on the test program on the website?

Thank you

  • Which ESP module are you using?
    – Fahad
    Apr 28, 2021 at 23:56
  • it's wroom ESP-32 Apr 29, 2021 at 14:15

1 Answer 1


SPI0 and SPI1 are used internally to access the ESP32’s attached flash memory. SPI2 and SPI3 are general purpose SPI controllers, sometimes referred to as HSPI and VSPI, respectively. They are open to users.

A quick google search shows:

ESP32 Wroom Pinout

So you can use IO5, IO18, IO19 and IO23.

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